VALENTINIAN I., Roman emperor of the West from A.D. 364 to 375, was born at Cibalis, in Pannonia. He had been an officer of the guard under Julian and Jovian, and had risen high in the imperial service. He was chosen emperor in his forty-third year by the officers of the army at Nicaea in Bithynia in 364, and shortly afterwards named his brother Valens (q.v.) colleague with him in the empire. As emperor of the West, Valentinian took Italy, Illyricum, Spain, the Gauls, Britain and Africa, leaving to Valens the eastern half of the Balkan Peninsula, Greece, Egypt, Syria and Asia Minor as far as Persia. During the short reign of Valentinian there were wars in Africa, in Germany and in Britain, and Rome came into collision with the Burgundians, Saxons and Alamanni. The emperor's chief work was guarding the frontiers and establishing military positions. Milan was at first his headquarters for settling the affairs of northern Italy; next year (365) he was at Paris, and then at Reims, to direct the operations of his generals against the Alamanni who were driven back to the German bank of the Rhine, and checked for a while by a chain of military posts and fortresses. At the close of 367, however, they suddenly crossed the Rhine, and sacked Moguntia cum (Mainz). Valentinian attacked them at Solicinium (Sulz in the Neckar valley or Schwetzingen) with a large army, and de feated them with considerable loss on his own part. (Later, in 374, he made peace with their king, Macrianus.) The next three years he spent at Trier, which he chiefly made his headquarters, organ izing the defence of the Rhine frontier.
During his reign the coasts of Gaul were harassed by the Saxon pirates, with whom the Picts and Scots of northern Britain joined hands, and ravaged the island from the wall of Antoninus to the shores of Kent. In 368 Theodosius was sent to drive back the
invaders; in this he was completely successful, and established a new British province, called Valentia. In Africa the Moorish prince, Firmus, raised the standard of revolt against Count Ro manus, the military governor. The services of Theodosius were again requisitioned. He landed in Africa with a small band of veterans, and Firmus, to avoid being taken prisoner, committed suicide. In 374 the Quadi, a German tribe in what is now Moravia and Hungary, resenting the erection of Roman forts to the north of the Danube, and further exasperated by the treacherous murder of their king, Gabinius, crossed the river and laid waste the prov ince of Pannonia. The emperor, in April of the following year, entered Illyricum with a powerful army, but during an audience to an embassy from the Quadi at Brigetio on the Danube (near Pressburg) died in a fit of apoplexy.
Valentinian's general administration seems to have been thor oughly honest and able, in some respects beneficent. If he was hard and exacting in the matter of taxes, he spent them in the defence and improvement of his dominions. Though himself a plain and almost illiterate soldier, he was a founder of schools, and he also provided medical attendance for the poor of Rome, by appointing a physician for each of the fourteen districts of the city. He was an orthodox Catholic, but he permitted absolute religious freedom to all his subjects. The great blot on his mem ory is his cruelty, which at times was frightful.
See Ammianus Marcellinus xxv.–xxx.; Gibbon, Decline and Fall, chap. 25 ; T. Hodgkin, Italy and her Invaders, bk. i. chap. 3 ; H. Richter, Das westromische Reich (1865), pp. 24o-268.